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package java.awt;

/**
 * The <code>GridLayout</code> class is a layout manager that
 * lays out a container's components in a rectangular grid.
 * The container is divided into equal-sized rectangles,
 * and one component is placed in each rectangle.
 * For example, the following is an applet that lays out six buttons
 * into three rows and two columns:
 *
 * <hr><blockquote>
 * <pre>
 * import java.awt.*;
 * import java.applet.Applet;
 * public class ButtonGrid extends Applet {
 *     public void init() {
 *         setLayout(new GridLayout(3,2));
 *         add(new Button("1"));
 *         add(new Button("2"));
 *         add(new Button("3"));
 *         add(new Button("4"));
 *         add(new Button("5"));
 *         add(new Button("6"));
 *     }
 * }
 * </pre></blockquote><hr>
 * <p>
 * If the container's <code>ComponentOrientation</code> property is horizontal
 * and left-to-right, the above example produces the output shown in Figure 1.
 * If the container's <code>ComponentOrientation</code> property is horizontal
 * and right-to-left, the example produces the output shown in Figure 2.
 *
 * <table style="float:center" WIDTH=600 summary="layout">
 * <tr ALIGN=CENTER>
 * <td><img SRC="doc-files/GridLayout-1.gif"
 * alt="Shows 6 buttons in rows of 2. Row 1 shows buttons 1 then 2.
 * Row 2 shows buttons 3 then 4. Row 3 shows buttons 5 then 6.">
 * </td>
 *
 * <td ALIGN=CENTER><img SRC="doc-files/GridLayout-2.gif"
 * alt="Shows 6 buttons in rows of 2. Row 1 shows buttons 2 then 1.
 * Row 2 shows buttons 4 then 3. Row 3 shows buttons 6 then 5.">
 * </td>
 * </tr>
 *
 * <tr ALIGN=CENTER>
 * <td>Figure 1: Horizontal, Left-to-Right</td>
 *
 * <td>Figure 2: Horizontal, Right-to-Left</td>
 * </tr>
 * </table>
 * <p>
 * When both the number of rows and the number of columns have
 * been set to non-zero values, either by a constructor or
 * by the <tt>setRows</tt> and <tt>setColumns</tt> methods, the number of
 * columns specified is ignored.  Instead, the number of
 * columns is determined from the specified number of rows
 * and the total number of components in the layout. So, for
 * example, if three rows and two columns have been specified
 * and nine components are added to the layout, they will
 * be displayed as three rows of three columns.  Specifying
 * the number of columns affects the layout only when the
 * number of rows is set to zero.
 *
 * @author Arthur van Hoff
 * @since JDK1.0
 */
public class GridLayout implements LayoutManager, java.io.Serializable {

  /*
   * serialVersionUID
   */
  private static final long serialVersionUID = -7411804673224730901L;

  /**
   * This is the horizontal gap (in pixels) which specifies the space
   * between columns.  They can be changed at any time.
   * This should be a non-negative integer.
   *
   * @serial
   * @see #getHgap()
   * @see #setHgap(int)
   */
  int hgap;
  /**
   * This is the vertical gap (in pixels) which specifies the space
   * between rows.  They can be changed at any time.
   * This should be a non negative integer.
   *
   * @serial
   * @see #getVgap()
   * @see #setVgap(int)
   */
  int vgap;
  /**
   * This is the number of rows specified for the grid.  The number
   * of rows can be changed at any time.
   * This should be a non negative integer, where '0' means
   * 'any number' meaning that the number of Rows in that
   * dimension depends on the other dimension.
   *
   * @serial
   * @see #getRows()
   * @see #setRows(int)
   */
  int rows;
  /**
   * This is the number of columns specified for the grid.  The number
   * of columns can be changed at any time.
   * This should be a non negative integer, where '0' means
   * 'any number' meaning that the number of Columns in that
   * dimension depends on the other dimension.
   *
   * @serial
   * @see #getColumns()
   * @see #setColumns(int)
   */
  int cols;

  /**
   * Creates a grid layout with a default of one column per component,
   * in a single row.
   *
   * @since JDK1.1
   */
  public GridLayout() {
    this(1, 0, 0, 0);
  }

  /**
   * Creates a grid layout with the specified number of rows and
   * columns. All components in the layout are given equal size.
   * <p>
   * One, but not both, of <code>rows</code> and <code>cols</code> can
   * be zero, which means that any number of objects can be placed in a
   * row or in a column.
   *
   * @param rows the rows, with the value zero meaning any number of rows.
   * @param cols the columns, with the value zero meaning any number of columns.
   */
  public GridLayout(int rows, int cols) {
    this(rows, cols, 0, 0);
  }

  /**
   * Creates a grid layout with the specified number of rows and
   * columns. All components in the layout are given equal size.
   * <p>
   * In addition, the horizontal and vertical gaps are set to the
   * specified values. Horizontal gaps are placed between each
   * of the columns. Vertical gaps are placed between each of
   * the rows.
   * <p>
   * One, but not both, of <code>rows</code> and <code>cols</code> can
   * be zero, which means that any number of objects can be placed in a
   * row or in a column.
   * <p>
   * All <code>GridLayout</code> constructors defer to this one.
   *
   * @param rows the rows, with the value zero meaning any number of rows
   * @param cols the columns, with the value zero meaning any number of columns
   * @param hgap the horizontal gap
   * @param vgap the vertical gap
   * @throws IllegalArgumentException if the value of both <code>rows</code> and <code>cols</code>
   * is set to zero
   */
  public GridLayout(int rows, int cols, int hgap, int vgap) {
    if ((rows == 0) && (cols == 0)) {
      throw new IllegalArgumentException("rows and cols cannot both be zero");
    }
    this.rows = rows;
    this.cols = cols;
    this.hgap = hgap;
    this.vgap = vgap;
  }

  /**
   * Gets the number of rows in this layout.
   *
   * @return the number of rows in this layout
   * @since JDK1.1
   */
  public int getRows() {
    return rows;
  }

  /**
   * Sets the number of rows in this layout to the specified value.
   *
   * @param rows the number of rows in this layout
   * @throws IllegalArgumentException if the value of both <code>rows</code> and <code>cols</code>
   * is set to zero
   * @since JDK1.1
   */
  public void setRows(int rows) {
    if ((rows == 0) && (this.cols == 0)) {
      throw new IllegalArgumentException("rows and cols cannot both be zero");
    }
    this.rows = rows;
  }

  /**
   * Gets the number of columns in this layout.
   *
   * @return the number of columns in this layout
   * @since JDK1.1
   */
  public int getColumns() {
    return cols;
  }

  /**
   * Sets the number of columns in this layout to the specified value.
   * Setting the number of columns has no affect on the layout
   * if the number of rows specified by a constructor or by
   * the <tt>setRows</tt> method is non-zero. In that case, the number
   * of columns displayed in the layout is determined by the total
   * number of components and the number of rows specified.
   *
   * @param cols the number of columns in this layout
   * @throws IllegalArgumentException if the value of both <code>rows</code> and <code>cols</code>
   * is set to zero
   * @since JDK1.1
   */
  public void setColumns(int cols) {
    if ((cols == 0) && (this.rows == 0)) {
      throw new IllegalArgumentException("rows and cols cannot both be zero");
    }
    this.cols = cols;
  }

  /**
   * Gets the horizontal gap between components.
   *
   * @return the horizontal gap between components
   * @since JDK1.1
   */
  public int getHgap() {
    return hgap;
  }

  /**
   * Sets the horizontal gap between components to the specified value.
   *
   * @param hgap the horizontal gap between components
   * @since JDK1.1
   */
  public void setHgap(int hgap) {
    this.hgap = hgap;
  }

  /**
   * Gets the vertical gap between components.
   *
   * @return the vertical gap between components
   * @since JDK1.1
   */
  public int getVgap() {
    return vgap;
  }

  /**
   * Sets the vertical gap between components to the specified value.
   *
   * @param vgap the vertical gap between components
   * @since JDK1.1
   */
  public void setVgap(int vgap) {
    this.vgap = vgap;
  }

  /**
   * Adds the specified component with the specified name to the layout.
   *
   * @param name the name of the component
   * @param comp the component to be added
   */
  public void addLayoutComponent(String name, Component comp) {
  }

  /**
   * Removes the specified component from the layout.
   *
   * @param comp the component to be removed
   */
  public void removeLayoutComponent(Component comp) {
  }

  /**
   * Determines the preferred size of the container argument using
   * this grid layout.
   * <p>
   * The preferred width of a grid layout is the largest preferred
   * width of all of the components in the container times the number of
   * columns, plus the horizontal padding times the number of columns
   * minus one, plus the left and right insets of the target container.
   * <p>
   * The preferred height of a grid layout is the largest preferred
   * height of all of the components in the container times the number of
   * rows, plus the vertical padding times the number of rows minus one,
   * plus the top and bottom insets of the target container.
   *
   * @param parent the container in which to do the layout
   * @return the preferred dimensions to lay out the subcomponents of the specified container
   * @see java.awt.GridLayout#minimumLayoutSize
   * @see java.awt.Container#getPreferredSize()
   */
  public Dimension preferredLayoutSize(Container parent) {
    synchronized (parent.getTreeLock()) {
      Insets insets = parent.getInsets();
      int ncomponents = parent.getComponentCount();
      int nrows = rows;
      int ncols = cols;

      if (nrows > 0) {
        ncols = (ncomponents + nrows - 1) / nrows;
      } else {
        nrows = (ncomponents + ncols - 1) / ncols;
      }
      int w = 0;
      int h = 0;
      for (int i = 0; i < ncomponents; i++) {
        Component comp = parent.getComponent(i);
        Dimension d = comp.getPreferredSize();
        if (w < d.width) {
          w = d.width;
        }
        if (h < d.height) {
          h = d.height;
        }
      }
      return new Dimension(insets.left + insets.right + ncols * w + (ncols - 1) * hgap,
          insets.top + insets.bottom + nrows * h + (nrows - 1) * vgap);
    }
  }

  /**
   * Determines the minimum size of the container argument using this
   * grid layout.
   * <p>
   * The minimum width of a grid layout is the largest minimum width
   * of all of the components in the container times the number of columns,
   * plus the horizontal padding times the number of columns minus one,
   * plus the left and right insets of the target container.
   * <p>
   * The minimum height of a grid layout is the largest minimum height
   * of all of the components in the container times the number of rows,
   * plus the vertical padding times the number of rows minus one, plus
   * the top and bottom insets of the target container.
   *
   * @param parent the container in which to do the layout
   * @return the minimum dimensions needed to lay out the subcomponents of the specified container
   * @see java.awt.GridLayout#preferredLayoutSize
   * @see java.awt.Container#doLayout
   */
  public Dimension minimumLayoutSize(Container parent) {
    synchronized (parent.getTreeLock()) {
      Insets insets = parent.getInsets();
      int ncomponents = parent.getComponentCount();
      int nrows = rows;
      int ncols = cols;

      if (nrows > 0) {
        ncols = (ncomponents + nrows - 1) / nrows;
      } else {
        nrows = (ncomponents + ncols - 1) / ncols;
      }
      int w = 0;
      int h = 0;
      for (int i = 0; i < ncomponents; i++) {
        Component comp = parent.getComponent(i);
        Dimension d = comp.getMinimumSize();
        if (w < d.width) {
          w = d.width;
        }
        if (h < d.height) {
          h = d.height;
        }
      }
      return new Dimension(insets.left + insets.right + ncols * w + (ncols - 1) * hgap,
          insets.top + insets.bottom + nrows * h + (nrows - 1) * vgap);
    }
  }

  /**
   * Lays out the specified container using this layout.
   * <p>
   * This method reshapes the components in the specified target
   * container in order to satisfy the constraints of the
   * <code>GridLayout</code> object.
   * <p>
   * The grid layout manager determines the size of individual
   * components by dividing the free space in the container into
   * equal-sized portions according to the number of rows and columns
   * in the layout. The container's free space equals the container's
   * size minus any insets and any specified horizontal or vertical
   * gap. All components in a grid layout are given the same size.
   *
   * @param parent the container in which to do the layout
   * @see java.awt.Container
   * @see java.awt.Container#doLayout
   */
  public void layoutContainer(Container parent) {
    synchronized (parent.getTreeLock()) {
      Insets insets = parent.getInsets();
      int ncomponents = parent.getComponentCount();
      int nrows = rows;
      int ncols = cols;
      boolean ltr = parent.getComponentOrientation().isLeftToRight();

      if (ncomponents == 0) {
        return;
      }
      if (nrows > 0) {
        ncols = (ncomponents + nrows - 1) / nrows;
      } else {
        nrows = (ncomponents + ncols - 1) / ncols;
      }
      // 4370316. To position components in the center we should:
      // 1. get an amount of extra space within Container
      // 2. incorporate half of that value to the left/top position
      // Note that we use trancating division for widthOnComponent
      // The reminder goes to extraWidthAvailable
      int totalGapsWidth = (ncols - 1) * hgap;
      int widthWOInsets = parent.width - (insets.left + insets.right);
      int widthOnComponent = (widthWOInsets - totalGapsWidth) / ncols;
      int extraWidthAvailable = (widthWOInsets - (widthOnComponent * ncols + totalGapsWidth)) / 2;

      int totalGapsHeight = (nrows - 1) * vgap;
      int heightWOInsets = parent.height - (insets.top + insets.bottom);
      int heightOnComponent = (heightWOInsets - totalGapsHeight) / nrows;
      int extraHeightAvailable =
          (heightWOInsets - (heightOnComponent * nrows + totalGapsHeight)) / 2;
      if (ltr) {
        for (int c = 0, x = insets.left + extraWidthAvailable; c < ncols;
            c++, x += widthOnComponent + hgap) {
          for (int r = 0, y = insets.top + extraHeightAvailable; r < nrows;
              r++, y += heightOnComponent + vgap) {
            int i = r * ncols + c;
            if (i < ncomponents) {
              parent.getComponent(i).setBounds(x, y, widthOnComponent, heightOnComponent);
            }
          }
        }
      } else {
        for (int c = 0, x = (parent.width - insets.right - widthOnComponent) - extraWidthAvailable;
            c < ncols; c++, x -= widthOnComponent + hgap) {
          for (int r = 0, y = insets.top + extraHeightAvailable; r < nrows;
              r++, y += heightOnComponent + vgap) {
            int i = r * ncols + c;
            if (i < ncomponents) {
              parent.getComponent(i).setBounds(x, y, widthOnComponent, heightOnComponent);
            }
          }
        }
      }
    }
  }

  /**
   * Returns the string representation of this grid layout's values.
   *
   * @return a string representation of this grid layout
   */
  public String toString() {
    return getClass().getName() + "[hgap=" + hgap + ",vgap=" + vgap +
        ",rows=" + rows + ",cols=" + cols + "]";
  }
}
